ICB2FL02G Datasheet, PDF (23/55 Pages) Infineon Technologies AG – Smart Ballast Control IC for Fluorescent Lamp Ballasts

2^nd Generation FL-Controller for FL-Ballasts
Functional Description
2.4.4 THD Correction via ZCD Signal
An additional feature is the THD correction (Figure 16). In order to optimize the improved THD
(especially in the zones A shown in Figure 17 ZCD @ AC Input Voltage), there is a possibility to
extend pulse width of the gate signal (blue part of the PFC gate signal in Figure 17) via variable PFC
ZCD resistor (see Resistor R13 in Figure 3) in addition to the gate signal controlled by the V_PFCVS
signal (gray part of the PFC gate signal in Figure 17).
Figure 17 THD Optimization using adjustable Pulse Width Extension
In case of DC input voltage (see DC Input Voltage in Figure 17), the pulse width gate signal is fixed as
a combination of the gate signal controlled by the V_PFCVS pin (gray) and the additional pulse width
signal controlled by the ZCD pin (blue) shown in Figure 17 ZCD @ DC Input Voltage.
The PFC current limitation at pin PFCCS interrupts the ON – time of the PFC MOSFET if the voltage
drop at the shunt resistors R18 (Figure 3) exceeds the V_PFCCS = 1.0 V (Figure 16). This interrupt will
restart after the next sufficient signal from ZCD is available (Auto Restart). The first value of the
resistor can be calculated by the ratio of the PFC mains choke and ZCD winding the bus voltage and a
current of typically 1.5 mA (see equation below). An adjustment of the ZCD resistor causes an
optimized THD.
R_ZCD
=
N _ZCD
N _PFC
*V_BUS
1.5mA
Equation 1 R_ZCD a good pratical Value
Preliminary Datasheet
Page 23 of 55
ICB2FL02G
V1.2